Plant trays have long been widely used in plant nurseries and greenhouses for initially growing seedlings prior to subsequent transplanting into plant flats, other conventional plant receptacles, or directly into a field or planting bed. These prior art plant trays include an array of individual plant cells. Each plant cell holds growth media such as soil or peat and a young, small plant. Some of these prior art plant trays are typically designed to be used in conjunction with automatic transplanters that automatically eject the small plants through an open bottom formed in the plant tray of each plant cell. To facilitate plant ejection, the plant cells of prior art plant trays have included a truncated pyramid shape, wherein the bottom of the cell has a greater cross-sectional area than the top. This enables the plant and associated media to be induced through the open bottom of the plant tray by vacuum.
A problem that has arisen with prior art plant trays is their durability during use with automatic transplanters. Typical prior art plant trays are formed from relatively flimsy, lightweight vacuum-molded plastic. The individual plant cells are therefore easily damaged or broken during transplanting. In addition, the flimsy, flexible nature of typical vacuum-molded plant trays often results in deformation or flexing of the cells as plants are ejected during transplanting. This can result in damage to the young, fragile plants and can also effect the ability of a transplanter to carry out precision planting.
One reason that prior art plant trays are not always compatible with automatic transplanters is that they are not precision molded. Automatic transplanters typically use indexing grooves formed on the sides of the plant tray to move the plant tray in small increments. A plant ejection mechanism typically induces the plant out through the bottom of the tray. If the plant tray is not precision molded and is resultingly misaligned on the automatic transplanter, then ejection from the tray is virtually impossible.
Also, typical vacuum-molded plant trays are not readily reusable because in part they are not easily cleaned. Therefore, because of their fragile construction and the need to clean them, typical plant trays are generally not reused but are used only once and then discarded.
Yet another problem that exists with typical prior art plant trays is that they are not designed to be numerically compatible with conventional plant flats, which typically have 24, 36, 48, or 72 individual plant receiving cavities. Typical prior art plant trays do not have a number of plant cells that is divisible by each of these numbers. Therefore, when a typical prior art plant tray is used with an automatic transplanter and a conventional plant flat, some plants may have to be transplanted by hand if the plant tray runs out of plants before the plant flat is completely filled. Alternately, an odd number of plants may remain in the plant tray after the plant flats are completely filled.
In view of the above, an object of the present invention is to provide a rugged plant tray with greater strength and durability than previously designed vacuum-molded plant trays so that the plant tray better protects plants during transplanting and so that the plant tray can be cleaned and reused.
Another object of the present invention is to provide a plant tray that resists deformation and flexing during use with an automatic transplanter for precise transplanting.
Yet another object of the present invention is to provide a plant tray that is precision molded so that it may be properly aligned on an automatic transplanter such that the plant cells of the tray will automatically and repeatedly align with an existing opening associated with the transplanter.
Still another object of the present invention is provide a plant tray that includes a predetermined number of plant cells that is divisible by 24, 36, 48, and 72 so that the plant tray is numerically compatible with conventional plant flats.